And he said he looked forward to the day when the party would itself take part in the Pride event.

"We've been slow," but we've changed," he added.

Organisers said they had noticed a rise in corporate bodies wanting to associate themselves with the festival.

Mr Nesbitt said Belfast Pride had become more self-assured than ever.

"It was a very positive day with a huge number of people taking part," the former UUP leader said. "I haven't witnessed a Pride event for a long time and I sensed a huge change in the atmosphere.

"A long time ago it was a lot less confident, with organisers and participants feeling they had to be a lot more in your face.

"Saturday was just a celebration and I felt everyone taking part were beyond having to prove themselves."

He added: "The other big difference I noticed was the number of private companies and public bodies throwing their support behind it all."

The first Belfast Pride parade held in 1991 attracted a small crowd of just around 100.

Taking part for the second year in a row were officers in uniform from both the PSNI and An Garda Siochana.

Members of the NI Ambulance Service also took part in the celebrations.

A Marks & Spencer employee in Bangor called Steven was congratulated on social media by his employers after proposing to his partner Sam at the event, surrounded by his colleagues.

As Northern Ireland remains the only part of the UK and Ireland not to legalise same-sex marriage, many campaigners still view Pride as a protest.

The Love Equality campaign has called on the Prime Minister Theresa May to change the law. Patrick Corrigan, NI director of Amnesty International, said: "Pride is always the most colourful day of the year in Belfast. This year it is bigger and brighter than ever.

"People on the streets of Belfast today are sick of a second-class citizenship based on who they are and where they live.

"Theresa May and (Secretary of State) Karen Bradley should be ashamed that 18 months after the collapse of devolution, same-sex couples in Northern Ireland are still waiting to be treated as equals. This is now in their hands."